Urinary Bacterial Isolate Distribution and Laboratory-Reported Antimicrobial Resistance in a Romanian Tertiary Urology Department: A Retrospective Comparison of 2013 and 2023

Background and Objectives: Urinary bacterial ecology and antimicrobial resistance may change over time and vary across clinical settings. This study compared urinary bacterial isolate distributions and resistance patterns in a tertiary Romanian urology department in 2013 and 2023. Materials and Methods: This retrospective, single-center, laboratory-based study compared two cross-sectional snapshots from 2013 and 2023, comprising 642 bacterial isolate records from urine specimens (265 in 2013 and 377 in 2023). Organisms were harmonized into comparable taxonomic groups. Escherichia coli (E. coli) resistance was compared for antimicrobial agents with at least 30 interpretable results in each year using Fisher’s exact test with false discovery rate correction. Sensitivity analyses excluded exact duplicate records and intermediate susceptibility results. Results: The overall organism distribution differed significantly between years (p < 0.001). The proportion of Enterococcus spp. increased from 9.1% to 56.8%, whereas the proportion of Klebsiella spp. decreased from 91/265 (34.3%) to 2/377 (0.5%). The relative proportion of E. coli was similar in both years (30.9% versus 31.0%). Among E. coli isolates, the proportions reported as resistant were lower in 2023 for cefepime (20.8% to 0.9%), ceftazidime (24.6% to 1.8%), and gentamicin (25.0% to 3.3%). For piperacillin–tazobactam, the proportion reported as resistant was 4.6% in 2013 and 21.6% in 2023; however, counting the 11 intermediate 2013 results as resistant yielded 14/65 (21.5%), similar to the 2023 proportion. No significant differences were detected for cefuroxime, ciprofloxacin, levofloxacin, or meropenem. The overall organism-distribution difference persisted in the conservative profile-collapse analysis, whereas none of the E. coli antimicrobial resistance (AMR) comparisons remained statistically significant after FDR correction in that analysis, although resistance breakpoints could not be harmonized retrospectively. Conclusions: The two study years differed in urinary bacterial isolate composition and selected laboratory-reported E. coli resistance proportions. These findings support continued local surveillance, but changes in laboratory methods and susceptibility standards limit attribution of the observed differences to biological changes in resistance.